Accessory Structures in West Allis, WI: What Residents Actually Need to Know

If you live in West Allis or are thinking about moving there, accessory structures are one of those things you probably won't think about until they affect you directly. West Allis has 2 specific rules on the books covering different aspects of accessory structures, and some of them might surprise you.

Shed Rules

Sheds in West Allis are 'Other Accessory Buildings' under Section 19.42 of the West Allis Zoning Code. They are limited to 300 square feet, 15 feet in height, must sit at least 3 feet from any side or rear lot line (5 feet if the rear abuts an alley), at least 10 feet from the principal dwelling, and at least 60 feet from the front lot line.

Key details: Code Section: Sec. 19.42. Max Size (Shed): 300 sq ft. Max Height: 15 feet. Side / Rear Setback: 3 feet. Distance From House: 10 feet.

A shed installed in the front yard, exceeding 300 square feet, taller than 15 feet, or inside the 3-foot side or rear lot-line setback (5 feet if abutting an alley) violates Section 19.42 of the West Allis Zoning Code and is enforceable by West Allis Code Enforcement and Building Inspections. Typical responses include a written notice of violation, an order to relocate or remove the shed, after-the-fact permit fees, and ongoing forfeitures under the West Allis Revised Municipal Code for continued non-compliance.

ADU Rules

West Allis regulates accessory buildings under Chapter 19 (Zoning) of the Revised Municipal Code, adopted under the city zoning authority of Wis. Stat. Sec. 62.23. Sec. 19.42 (Residential Accessory Buildings) caps detached accessory structures at 50% of the principal building area, not to exceed 800 square feet, with a maximum exterior wall height of 20 feet. Setback minimums include 10 feet from the principal building, 3 feet from side lot lines, and 3-5 feet from rear lot lines depending on alley adjacency. The West Allis Zoning Code does not establish a separate by-right accessory dwelling unit (ADU) class in the manner of cities like Appleton; a habitable second dwelling unit on a single-family lot generally requires zoning interpretation by the Planning and Zoning Department.

Key details: Authority: Chapter 19 is the West Allis Zoning Ordinance (Wis. Stat. Sec. 62.23 authority). Authority: Sec. 19.42 governs Residential Accessory Buildings. Material: Detached accessory building max: 800 sq ft and 50% of principal building area. Height: Maximum exterior wall height: 20 feet. Authority: Minimum 10 ft separation from principal building.

Constructing an accessory building that exceeds the size, height, or setback limits of Sec. 19.42, or occupying an accessory structure as a separate dwelling unit without zoning approval, violates Chapter 19 of the West Allis Revised Municipal Code. Enforcement may include stop-work orders, daily forfeitures under the city's general penalty provisions, and orders to remove or modify nonconforming construction. Permits and inspections are administered by Building Inspections and Neighborhood Services.

The Bottom Line

West Allis's accessory structures rules are a mixed bag. Some areas are strict, others are relaxed, and the details matter. The best approach is to check the specific rule that applies to your situation rather than assuming West Allis is broadly strict or permissive.

All of the above reflects West Allis's municipal code as of our last review. If you need specifics on fines, exemptions, or filing requirements, the detailed ordinance pages linked above have the full breakdown.